I don't know where to start

I have been skin picking for as long as I can remember, at least since I was 14 when I got bullied about it. I'm now 22 and have been trying for years to stop it but as soon as things get hard I start picking and I don't really notice I'm doing it until I notice the blood on my hand. Recently it has gotten worse, I don't just pick my face but my arms, back, legs and feet. At times I have picked so much skin off my heels that every step hurts. My girlfriend has decided that it's my problem and the fact that I haven't stopped shows that I'm not really trying and therefore I don't deserve her support in stopping. My family are either too oblivious to notice anything is going on or they don't care. I want to stop but as soon as I start making progress things get stresful again and it just happens. I feel like no one understands what it's like, my girlfriend tells me that all I need to do is stop and it's not that hard but for me it is. I don't want to do this anymore because it hurts and it's leaving scars and it gets in the way of my life but I don't know how to stop, I've tried doing a different behaviour but as soon as my hand goes anywhere near my face I start picking and the different behaviours get in the way of other things I need to do like taking notes in lectures. What works and where do I start?